Why is auditioning so scary?
If you ask any flute player what the scariest thing about flute playing is, will either be playing in front of an audience, or auditioning.
Auditioning is the process of which you display your abilities to an adjudicator, and in our case, you would probably play a flute solo or exercise for an adjudicator. It may not even be that you are scared of auditioning; but of the fact that someone is judging your playing critically.
While most people practice by themselves, as soon as you get in front of that judge, everything that you had practiced for goes to the back of your mind, and you start to get nervous.
What can I do?
There are many things that you can do to prevent the mental break down at the audition.
Since you will be performing in front of someone who will judge you critically, try finding someone else to play for that will judge you critically as well. Many times, these people will be friends or family that you trust to give you the honest truth in the matter.
Also, try recording yourself playing if you are nervous that you aren't hearing everything wrong while you are in the process of practicing. You can also review things that you forgot while you are playing, such as wrong notes, or breaks in your playing.